Aqueous solution of olanexidine, method of preparing the aqueous solution, and disinfectant

ABSTRACT

The present invention provides a disinfectant that contains olanexidine in a concentration sufficient to exhibit an effective bactericidal effect, and that has hardly any side effects such as skin irritation. Specifically, the present invention provides a disinfectant containing an aqueous solution that contains olanexidine and at least an equimolar amount of gluconic acid, and substantially contains neither an acid other than gluconic acid nor a salt of the acid other than gluconic acid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.10/557,736, filed Mar. 9, 2006; which is a 371 of PCT/JP2004/007434,filed May 25, 2004; the entire disclosures of each of which are herebyincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an aqueous solution containingolanexidine, a method of preparing the aqueous solution, and adisinfectant containing the aqueous solution.

BACKGROUND ART

Olanexidine is a compound with high bactericidal activity having thechemical name 1-(3,4-dichlorobenzyl)-5-octylbiguanide. Research has beencarried out into bactericides containing olanexidine hydrochloride as anactive ingredient (see Japanese Patent No. 2662343, etc.).

Olanexidine has very poor solubility in water, and hitherto known saltsof olanexidine are also poorly soluble in water. For example, thesolubility at 0° C. of olanexidine hydrochloride in water has beenmeasured to be less than 0.05% (W/V), and the solubility of freeolanexidine is a further order of magnitude less than this.Consequently, sufficient bactericidal activity cannot be expected of anaqueous solution merely having olanexidine dissolved therein, andmoreover, depending on the conditions the olanexidine may precipitateout.

In the case of making an aqueous preparation of olanexidine inparticular, to make the concentration of the olanexidine sufficient forexhibiting effective bactericidal activity, and to reduce thepossibility of the olanexidine precipitating out, it has thus beenconsidered necessary to use a dissolution aid such as a surfactant.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an aqueous solutionthat contains olanexidine at a concentration sufficient to exhibit aneffective bactericidal effect, and moreover is stable without allowingprecipitation of olanexidine even at a high concentration, a preparationmethod thereof, and a disinfectant containing the aqueous solution (or acomposition for disinfection).

The present inventors carried out extensive researches to attain theabove object, and as a result succeeded in obtaining an olanexidineaqueous solution that contains olanexidine at a concentration of atleast 0.1% (W/V). More specifically, the inventors neutralized oralkalized, for example, a suspension of an acid addition salt ofolanexidine with an aqueous solution of an alkali to obtain olanexidinein the free form, washed the free olanexidine thoroughly with water toremove the acid that had formed the acid addition salt of olanexidineand the alkali salt of the acid, and then added the free olanexidine toan aqueous gluconic acid solution. The aqueous solution thus obtainedwas a stable solution containing olanexidine at a concentrationincomparably higher than the concentration attained by dissolving freeolanexidine or a salt of olanexidine with an acid other than gluconicacid in water. With such an aqueous solution, it was no longer essentialto use a surfactant. Based on these findings, the present inventorscarried out further researches and accomplished the present invention.

Note that in Japanese Patent No. 2662343, various acids are listed asacids that form acid addition salts with monobiguanide derivatives, andgluconic acid is included among them. However, in Japanese Patent No.2662343, there is no specific mention of a gluconic acid salt ofolanexidine, and no such a salt is isolated, and moreover there is nodisclosure of a solution of such a salt. Furthermore, there is nosuggestion regarding the solubility of such a salt in water.

Specifically, the present invention relates to the following aqueoussolutions, preparation methods thereof, disinfectants (or compositionsfor disinfection), etc.

(1) An aqueous solution containing olanexidine and at least an equimolaramount of gluconic acid, and substantially containing neither an acid(s)other than gluconic acid nor a salt(s) of the acid(s) (i.e., the acid(s)other than gluconic acid).

(2) The aqueous solution according to (1) above, wherein theconcentration of olanexidine is 0.1 to 20% (W/V).

(3) The aqueous solution according to (2) above, wherein theconcentration of olanexidine is 10 to 20% (W/V).

(4) A method of preparing the aqueous solution according to any one of(1) through (3) above, comprising neutralizing or alkalizing an aqueoussuspension of an acid addition salt of olanexidine with an aqueoussolution of an alkali to precipitate a solid, washing the precipitatedsolid with water, and then dissolving the washed solid in a gluconicacid aqueous solution.

(5) The method according to (4) above, wherein the neutralization oralkalization is carried out at a temperature of 20 to 30° C.

(6) A disinfectant containing the aqueous solution according to any oneof (1) through (3) above.

(7) The disinfectant according to (6) above, wherein the disinfectant isan aqueous preparation.

(8) The disinfectant according to (7) above, wherein the concentrationof olanexidine is 0.001 to 20% (W/V).

(9) The disinfectant according to (6) above, wherein the disinfectant isan alcoholic preparation.

(10) The disinfectant according to (9) above, wherein the concentrationof olanexidine is 0.001 to 6% (W/V).

(11) The disinfectant according to any one of (6) through (10) above,which further contains a polyalkylene glycol.

(12) The disinfectant according to (11) above, wherein the concentrationof the polyalkylene glycol is 0.5 to 10% (W/V).

(13) The disinfectant according to (11) or (12) above, wherein thepolyalkylene glycol is a polyethylene-polypropylene glycol or apolyethylene glycol.

(14) An aqueous solution containing olanexidine at a concentration of atleast 0.1% (W/V).

(15) Use of gluconic acid for solubilizing olanexidine in water.

(16) A method of disinfecting or sterilizing an object, comprisingcontacting the object with an effective amount of the disinfectantaccording to any one of (6) through (13) above.

(17) Use of a disinfectant according to any one of (6) through (13)above for disinfection or sterilization.

In the specification and claims, the concentration of each ingredient inan aqueous solution or disinfectant is, unless otherwise indicated,expressed as a weight per volume percentage “% (W/V)”, i.e., the weight(g) of each ingredient/100 mL of the aqueous solution or disinfectant.When the disinfectant is an alcoholic preparation, the concentration ofalcohol in the disinfectant is expressed as a volume per volumepercentage “% (V/V)”, i.e., the volume (mL) of alcohol/100 mL of thedisinfectant.

Moreover, in the specification and claims, the concentration ofolanexidine means the concentration of olanexidine in terms of the freeform in an aqueous solution or in a disinfectant, which is determined bymeasuring the amount of free olanexidine in the aqueous solution ordisinfectant by high-performance liquid chromatography.

DETAILED DESCRIPTION OF THE INVENTION Aqueous Solution

The present invention provides an aqueous solution containingolanexidine at a concentration of at least approximately 0.1% (W/V) interms of free olanexidine. The aqueous solution of the inventioncontains at least approximately 0.1% (W/V) olanexidine, and thereforecan be used in the manufacture of various forms of disinfectants inaccordance with the objective, including disinfectants that are dilutedat the time of use. Moreover even in the case of preparing adisinfectant having a relatively high olanexidine concentration from theaqueous solution of the invention, there is no longer any risk of theolanexidine precipitating out in the obtained disinfectant. It ispreferable that the olanexidine concentration in the aqueous solution beabout 0.1 to 20% (W/V). As described above, by solubilizing olanexidine,which is poorly soluble in water, the aqueous solution of the presentinvention has an outstanding advantage such that for the first time itcan be stably used in various forms of pharmaceutical preparations suchas liquids and ointments.

Olanexidine is a compound having the chemical name1-(3,4-dichlorobenzyl)-5-octylbiguanide represented by the followingformula (1).

An example of a preferable means for dissolving olanexidine in water ata concentration of at least about 0.1% (W/V) is to make at least anequimolar amount of gluconic acid, preferably 1 mole to a slight excessof gluconic acid per mole of the olanexidine, coexist with theolanexidine. In such an aqueous solution containing olanexidine and atleast an equimolar amount of gluconic acid, the olanexidine and thegluconic acid may form a salt, or the two may exist in the free form, orthe gluconic acid salt of olanexidine may coexist with free olanexidineand free gluconic acid.

Furthermore, it is preferable that the aqueous solution containingolanexidine and gluconic acid substantially contain neither an acidother than gluconic acid nor a salt of the acid (i.e., the acid otherthan gluconic acid). More specifically, it is preferable that theconcentration of any acid other than gluconic acid and an salt of theacid (i.e., the acid other than gluconic acid) in the aqueous solutionbe not more than approximately 0.05% (W/V). Here “acid other thangluconic acid” means a substance other than gluconic acid that provideshydrogen ions in an aqueous solution. Examples of “salt of the acidother than gluconic acid” include base addition salt of the acid, suchas a salt with an inorganic base, e.g., an alkali metal salt such as asodium salt or a potassium salt, an alkaline earth metal salt such as acalcium salt or a magnesium salt, an aluminium salt, or an ammoniumsalt; a salt with an organic base such as trimethylamine, triethylamine,pyridine, picoline, ethanolamine, diethanolamine, triethanolamine,dicylohexylamine or N,N-dibenzylethylenediamine; and so on.

Preparation Method of the Aqueous Solution

Described below is a preferable method of preparing an aqueous solutionthat contains olanexidine and gluconic acid, and substantially containneither an acid other than gluconic acid nor a salt of the acid (i.e.,the acid other than gluconic acid).

Olanexidine is generally obtained as a crystalline acid addition saltsuch as a hydrochloride. Therefore, the acid addition salt such asolanexidine hydrochloride is first suspended in water, and an alkalisuch as a sodium hydroxide or a potassium hydroxide is then added to thesuspension in the form of the alkali itself or in the form of an aqueousalkaline solution to precipitate free olanexidine. The amount of analkali to be added is such that free olanexidine can be precipitated,i.e., such that the suspension is neutral or alkaline. For example, theamount may be at least an equivalent relative to the acid forming theacid addition salt of olanexidine.

After the alkali addition, the mixture is stirred for about 1 to 5 hoursat about 0° C. to room temperature, preferably about 20 to 30° C., andmore preferably at a temperature in the vicinity of 25° C. In thepresent invention, the alkali may be an inorganic base or an organicbase such as those previously mentioned.

Next, the free olanexidine solid precipitated by the above treatment isfiltered off, and is washed with water to remove the acid that formedthe olanexidine acid addition salt and a salt of the acid and thealkali. After washing with water, the solid is resuspended in a solventsuch as water, is again filtered off, and is rewashed with water, and itis preferable to repeat this procedure once or several times.Additionally, if desired, free olanexidine of high purity can beobtained by dissolving the solid in a solvent such as an alcohol, andadding water to the solution to precipitate crystals of freeolanexidine. If the acid that formed the acid addition salt of theolanexidine and a salt of the acid and the alkali substantially remain,then the olanexidine in the aqueous solution may return to the poorlysoluble original salt.

Specifically, the residual amount of the acid that formed theolanexidine acid addition salt and a salt of the acid and the alkali inthe aqueous solution of the invention is preferably not more than about0.05% (W/V). For example, in the case of neutralizing or alkalizing asuspension of olanexidine hydrochloride with an aqueous sodium hydroxidesolution, it is preferable that the residual sodium chlorideconcentration in the aqueous solution be not more than about 0.05%(W/V).

Next, the solid obtained above is added to an aqueous gluconic acidsolution, or an aqueous gluconic acid solution is added to the solid,and the mixture is stirred, whereby the aqueous solution of theinvention can be obtained. This operation can be carried out at roomtemperature, but heating may be carried out as required. Theconcentration of the aqueous gluconic acid solution used can be suitablyselected so long as the aqueous solution contains at least an equimolaramount, specifically, about 1 to 1.1 moles of gluconic acid per mole offree olanexidine to be added thereto.

The aqueous gluconic acid solution used in this step can be prepared bydissolving gluconic acid itself, or can be prepared using a gluconicacid precursor that changes into gluconic acid in an aqueous solutionsuch as gluconolactone. As described earlier, if any acid other thangluconic acid or a salt of the acid (i.e., the acid other than gluconicacid) is present, then the olanexidine in the aqueous solution of thepresent invention may form a poorly soluble acid addition salt, andhence when preparing the aqueous gluconic acid solution, it is desirableto remove beforehand anions (e.g. chloride ions, bromide ions etc.) thatare produced from acids other than gluconic acid and that may form asalt, and salts of such anions with cations (such as sodium ions,potassium ions etc.). in the aqueous solution, such that such ions andsalts substantially do not remain in the aqueous gluconic acid solution.As described earlier, the preferable extent of the removal is such thatacids other than gluconic acid and salts of such acids remain in theaqueous solution at a concentration of not more than about 0.05% (W/V).

The above procedure gives an aqueous solution containing olanexidine andgluconic acid, and substantially containing neither an acid other thangluconic acid nor a salt of the acid. The aqueous solution obtainedremains in a clear transparent state at room temperature for a long timeeven if the olanexidine concentration is approximately 20% (W/V) interms of free olanexidine.

Disinfectant

The olanexidine aqueous solution of the present invention describedabove contains at least about 0.1% (W/V) olanexidine, and thus exhibitseffective disinfectant and bactericidal action, and hence is useful as adisinfectant. For example, the olanexidine aqueous solution of thepresent invention described above can be used as a disinfectant as such.

Alternatively, the olanexidine aqueous solution can be made into anaqueous preparation by diluting it with purified water, or, for example,can be made into an alcoholic preparation by diluting with an alcoholsuch as ethanol, isopropanol, or with denatured alcohol, and ifnecessary with a purified water.

Moreover, the olanexidine aqueous solution can be made more viscoususing a thickener or the like and can thus be made into a viscousdisinfectant. Alternatively, ethanol for disinfection or the like can beadded to the olanexidine aqueous solution, thus making the olanexidineaqueous solution into a quick-drying disinfectant that can be expectedto have both a quick-acting bactericidal effect due to the ethanol, anda sustained effect due to the olanexidine.

Furthermore, the olanexidine aqueous solution of the present inventioncan be used not only in the form of liquid preparations as describedabove but also in disinfectants in other suitable forms. Examples offorms other than liquid preparations include ointments, creams, gels,foams, aerosols, scrubs and so on. These forms can be prepared by usingcommonly used suitable carriers.

The olanexidine concentration in the disinfectant of the presentinvention is preferably adjusted to be 0.001 to 20% (W/V) in terms offree olanexidine.

When the disinfectant of the present invention is an alcoholicpreparation obtained by diluting it with an alcohol or denaturedalcohol, the bactericidal effect of the alcohol (specifically, ethanol,isopropanol, etc.) can be expected as well, and hence the concentrationof the olanexidine can be reduced. When the disinfectant of the presentinvention is an alcoholic preparation, the olanexidine concentration inthe disinfectant is preferably about 0.001 to 6% (W/V). In this case,the alcohol concentration in the disinfectant is preferably about thesame as that of ethanol for disinfection, i.e. about 70 to 85% (V/V).

If desired, a polyalkylene glycol can be further added to thedisinfectant of the present invention. Addition of a polyalkylene glycolto the disinfectant of the present invention produces the surprisingeffect of further reducing skin irritation without decreasing thebactericidal activity.

Specific examples of the polyalkylene glycol includepolyethylene-polypropylene glycols and polyethylene glycols. The typethereof (molecular weight, polymerization degree of ethylene oxide,polymerization degree of propylene oxide, etc.) can be suitably selectedfrom commonly used types in accordance with the form and application ofthe disinfectant and so on.

For example, preferable polyethylene-polypropylene glycols are thosehaving a polymerization degree of ethylene oxide (EO) of about 10 to 300(especially, about 15 to 200), and a polymerization degree of propyleneoxide (PO) of about 10 to 100 (especially, about 15 to 70). Preferablepolyethylene glycols are those having a molecular weight of 200 to10000.

A particularly preferable polyalkylene glycol is apolyethylene-polypropylene glycol with a polymerization degree of EO ofabout 15 to 200 and a polymerization degree of PO of about 15 to 70.

The amount of the polyalkylene glycol added can be suitably selected inaccordance with the form and application of the disinfectant, theconcentration of olanexidine and so on. Generally, the polyalkyleneglycol, if used, may be used at a concentration of about 0.01 to 50%(W/V) in the disinfectant, and preferably about 0.5 to 20% (W/V).

If desired, additives commonly used in preparations such as ordinaryliquid preparations, ointments and the like can be suitably added to thedisinfectant of the present invention insofar as it does not adverselyaffect the dissolution of olanexidine in water. Examples of suchadditives include preservatives, moisturizers, thickeners, nonionicsurfactants other than polyalkylene glycols, cationic surfactants,antioxidants, perfumes, colorants and so on, and also include otherbactericidal disinfectants and medicinal agents, etc. Note, however,that it is desirable to avoid the additives that are likely to form apoorly soluble acid addition salt with olanexidine, such as acids otherthan gluconic acid and salts of such acids, in particular citric acid,phosphoric acid, and salts thereof, etc.

Examples of the preservatives include p-oxybenzoic acid esters such asmethyl p-oxybenzoate, ethyl p-oxybenzoate and propyl p-oxybenzoate, andchlorhexidine gluconate.

Examples of the moisturizers include polyhydric alcohols such aspropylene glycol, 1,3-butanediol, polyethylene glycol and glycerol;synthetic macromolecular compounds such as carboxymethylcellulose andhydroxypropylcellulose; natural macromolecular compounds such as pectin,chitosan, chitin and xanthan gum; polysaccharides such as sorbitol,mannitol and xylitol; and fatty acid esters such as glyceroltriisooctanoate, isopropyl palmitate, isopropyl myristate and olive oil.

Examples of the thickeners include water-soluble polymers such ascarboxyvinyl polymers, cellulosic water-soluble macromolecularcompounds, povidones and polyvinyl alcohols. Carboxyvinyl polymers aremacromolecular compounds obtained by polymerizing carboxylic acids suchas acrylic acid or methacrylic acid, and generally, one having amolecular weight of about 1,000,000 to 3,000,000 is used. Examples ofcellulosic water-soluble macromolecular compounds includemethylcellulose, ethylcellulose, hydroxyethylcellulose,hydroxypropylcellulose, carboxymethylcellulose andhydroxypropylmethylcellulose.

Examples of the nonionic surfactants other than polyalkylene glycolsinclude lauric acid diethanolamide, coconut oil fatty aciddiethanolamide, coconut oil fatty acid monoethanolamide, lauric acidmonoisopropanolamide, oleic acid monoisopropanolamide, palm kernel oilfatty acid diethanolamide, and polyoxyethylene coconut oil fatty acidmonoethanolamide.

Examples of such cationic surfactants include a lauryl dimethyl amineoxide and alkyl dimethyl amine oxides, etc.

Examples of other bactericidal disinfectants that can be mixed with thedisinfectant of the present invention include surfactant bactericidaldisinfectants, and phenolic bactericidal disinfectants.

Examples of other medicaments that can be blended into the disinfectantof the present invention include local anesthetics, vasoconstrictors,adrenocortical hormones, antihistamines, astringents, antipruritics,analgesics/antiphlogistics, anti-trichophyton agents, sulfa drugs,keratolytics, and vitamins.

The disinfectant of the present invention has a broad antibacterialspectrum for various microbes. For example, the disinfectant has aneffective bactericidal and disinfectant action on gram-positive bacteriasuch as Staphylococci, Streptococci, Enterococci, and Listeria andPropionibacterium spp; and gram-negative bacteria such as Escherichiacoli, Shigella, Salmonella, Citrobacter, Klebsiella, Enterobacter,Serratia, Proteus, Morganella, Yersinia, Vibrio, Pseudomonas,Acinetobacter, Neisseria, Haemophilus, and Bacteroides spp.

The disinfectant also has an antiviral action for virus such asInfluenza virus with envelope, Human immunodeficiency virus, Herpessimplex virus, and Vesicular stomatitis virus, and has antifungal actionon yeast-like fungi such as Candida spp, Cryptococcus neoformans, andSaccharomyces cerevisiae.

The disinfectant of the present invention means an agent that can bewidely used for the purpose of killing, decreasing, or controlling etc.various microbes such as those described above.

The disinfectant of the present invention exhibits bactericidal anddisinfectant activities by contacting an object containing the microbeswith an effective amount of the disinfectant. Contacting methods are notparticularly limited, and specific examples thereof include immersion,spraying, bed bathing etc. Examples of the object include skin and/orhands of a human or animal, medical equipment, lavatories, bathrooms,furniture, articles and so on.

Therefore, the disinfectant of the present invention can be suitablyused for disinfecting skin/hands, skin subjected to surgery, skinwounded, medical equipment, operating rooms, sickrooms, furniture,equipment and other articles, etc.

Moreover, the aqueous solution or disinfectant of the present inventionmay be used by impregnating it in a base fabric. Examples of such basefabrics include cotton wool, gauze, paper, non-woven cloths, towels,other cloths and so on. Usable such base fabrics may bewater-decomposable or non-water-decomposable.

Effects of the Invention

The aqueous solution of the present invention has a broad antibacterialspectrum, and exhibits a rapidly appearing and a long-lastingbactericidal activity. Furthermore, the aqueous solution is very stableeven at high olanexidine concentration, and can thus be stored for along time. Moreover, the aqueous solution is excellent in terms ofsafety because of its low irritative and toxic properties. In addition,the aqueous solution has no problems with color, odor or taste, and canthus easily be made into preparations.

Furthermore, the aqueous solution also has the advantage of beingnoncorrosive, and hence can be widely used for disinfecting metallicmedical equipment, etc.

Best Mode for Carrying out the Invention

Following is a description of preferable examples, preparation examplesand test examples of the present invention; however the presentinvention is not limited to these examples.

Note that in the examples, “%” means “% (W/V)” unless otherwise stated.

The olanexidine concentration of each sample is measured usinghigh-performance liquid chromatography under the following conditions.

-   Column: stainless steel tube with an internal diameter of 4.6 mm and    a length of 15 cm filled with TSK gel Octyl-80Ts (manufactured by    Tosoh corporation)-   Temperature: 40° C.-   Solvent: a mixture of acetonitrile and 0.05 v/v % phosphoric acid    solution containing 10 mM sodium lauryl sulfate (volume ratio of    13:7).-   Detection method: absorbance at 237 nm was measured with an    ultraviolet absorption detector.

Example 1 Preparation of an Aqueous Solution Aqueous Solution 1

20.9 g (50 mmol) of olanexidine hydrochloride hemihydrate was added to250 mL of a 1 N aqueous sodium hydroxide solution, and the suspensionwas stirred for 1.5 hours at room temperature (25° C.). The solid wasfiltered off, and washed with water. The solid obtained was furthersuspended in 250 mL of purified water, the suspension was stirred for 5minutes at room temperature, and the solid was filtered off, and washedwith water. This operation was carried out once more to remove sodiumchloride formed. The solid obtained (free olanexidine) was put intopurified water in which 8.9 g (50 mmol) of gluconolactone had beendissolved, and the mixture was stirred at room temperature until thesolid dissolved, and then purified water was further added to give atotal volume of 300 mL. The concentration of olanexidine in the aqueoussolution obtained was measured by using high performance liquidchromatography to be 6% in terms of free olanexidine.

This aqueous solution was still transparent and colorless even afterbeing left for several months at room temperature.

Example 2 Aqueous Solution 2

62.7 g (150 mmol) of olanexidine hydrochloride hemihydrate was added to750 mL of a 1 N aqueous sodium hydroxide solution, and the suspensionwas stirred for 1.5 hours at room temperature (25° C.). The solid wasfiltered off and washed with water. The solid obtained was furthersuspended in 750 mL of purified water, the suspension was stirred for 5minutes at room temperature, and the solid was filtered off, and washedwith water. This operation was carried out once more to remove sodiumchloride formed. The solid obtained (free olanexidine) was put intopurified water in which 26.7 g (150 mmol) of gluconolactone had beendissolved, and the mixture was stirred at room temperature until thesolid dissolved, and then purified water was further added to give atotal volume of 300 mL. The concentration of olanexidine in the aqueoussolution obtained was measured by using high performance liquidchromatography to be 18% in terms of free olanexidine.

This aqueous solution was still transparent and colorless even afterbeing left for several months at room temperature.

Example 3 Aqueous Solution 3

69.8 g (167 mmol) of olanexidine hydrochloride hemihydrate was added to830 mL of a 1 N aqueous sodium hydroxide solution, and the suspensionwas stirred for 1.5 hours at room temperature (25° C.). The solid wasfiltered off, and washed with water. The solid obtained was furthersuspended in 830 mL of purified water, the suspension was stirred for 5minutes at room temperature, and the solid was filtered off, and washedwith water. This operation was carried out once more to remove sodiumchloride formed. The solid obtained (free olanexidine) was put intopurified water in which 29.7 g (167 mmol) of gluconolactone had beendissolved, and the mixture was stirred at room temperature until thesolid dissolved, and then purified water was further added to give atotal volume of 300 mL. The concentration of olanexidine in the aqueoussolution obtained was measured by using high performance liquidchromatography to be 20% in terms of free olanexidine.

This aqueous solution was still transparent and colorless even afterbeing left for several months at room temperature.

Preparation Example 1

20 mL of Aqueous Solution 1 obtained in Example 1 was diluted withpurified water to give a total volume of 240 mL. The solution was filledinto polyethylene bottles, and then high-pressure steam sterilizationwas carried out, thus obtaining a disinfectant containing 0.5%olanexidine.

Preparation Example 2

Absolute ethanol (purity 99.5%, the same hereinafter) was added to 60 mLof Aqueous Solution 1 obtained in Example 1, and the mixture wasuniformly mixed. Absolute ethanol was added thereto to give a totalvolume of 240 mL. The solution was filled aseptically into polyethylenebottles, thus obtaining a disinfectant containing 1.5% olanexidine.

Preparation Example 3

160 mL of absolute ethanol and 2 g of hydroxypropylcellulose were addedto 10 mL of Aqueous Solution 1 obtained in Example 1, and the mixturewas uniformly mixed. Purified water was added thereto to give a totalvolume of 200 mL. The solution was filled aseptically into polyethylenebottles, thus obtaining a viscous disinfectant containing 0.3%olanexidine.

Preparation Example 4

4.8 g of a polyethylene-polypropylene glycol (polymerization degree ofethylene oxide (EO): 160; polymerization degree of propylene oxide (PO):30) was added to 20 mL of Aqueous Solution 1 obtained in Example 1, andpurified water was added thereto to carry out dissolution and to give afinal volume of 240 mL. The solution was filled into polyethylenebottles, and then high-pressure steam sterilization was carried out,thus obtaining a disinfectant containing 0.5% olanexidine.

Preparation Example 5

2.4 g of a polyethylene-polypropylene glycol (polymerization degree ofEO: 196; polymerization degree of PO: 67) was added to 20 mL of AqueousSolution 1 obtained in Example 1, and purified water was added theretoto carry out dissolution and to give a final volume of 240 mL. Thesolution was filled into polyethylene bottles, and then high-pressuresteam sterilization was carried out, thus obtaining a disinfectantcontaining 0.5% olanexidine.

Preparation Example 6

19.2 g of polyethylene glycol 4000 was added to 20 mL of AqueousSolution 1 obtained in Example 1, and purified water was added theretoto carry out dissolution and to give a final volume of 240 mL. Thesolution was filled into polyethylene bottles, and then high-pressuresteam sterilization was carried out, thus obtaining a disinfectantcontaining 0.5% olanexidine.

Preparation Example 7

4.8 g of a polyethylene-polypropylene glycol (polymerization degree ofEO: 160; polymerization degree of PO: 30) was added to 60 mL of AqueousSolution 1 obtained in Example 1, and absolute ethanol was added theretoand uniformly mixed therewith so as to give a final volume of 240 mL.The solution was filled aseptically into polyethylene bottles, thusobtaining a disinfectant containing 1.5% olanexidine.

Preparation Example 8

160 mL of absolute ethanol, 2 g of hydroxypropylcellulose and 4.0 g of apolyethylene-polypropylene glycol (polymerization degree of EO: 160;polymerization degree of PO: 30) were added to 10 mL of Aqueous Solution1 obtained in Example 1, and the mixture was uniformly mixed. Purifiedwater was added thereto to give a final volume of 200 mL. The solutionwas filled aseptically into polyethylene bottles, thus obtaining viscousdisinfectants containing 0.3% olanexidine.

Preparation Example 9

9.0 g of a polyethylene-polypropylene glycol (polymerization degree ofEO: 160; polymerization degree of PO: 30) was added to 100 mL of AqueousSolution 2 obtained in Example 2, and purified water was added theretoto carry out dissolution and to give a final volume of 180 mL. Thesolution was filled into polyethylene bottles, and then high-pressuresteam sterilization was carried out, thus obtaining a disinfectantcontaining 10% olanexidine.

Preparation Example 10

1.2 g of a polyethylene-polypropylene glycol (polymerization degree ofEO: 20; polymerization degree of PO: 20) was added to 20 mL of AqueousSolution 1 obtained in Example 1, and purified water was added theretoto carry out dissolution and to give a final volume of 240 mL. Thesolution was filled into polyethylene bottles, and then high-pressuresteam sterilization was carried out, thus obtaining a disinfectantcontaining 0.5% olanexidine.

Preparation Example 11

240 mL of absolute ethanol, 15.0 g of glycerol, 15.0 g of glyceroltriisooctanoate and 0.6 g of a polyethylene-polypropylene glycol(polymerization degree of EO: 20; polymerization degree of PO: 20) wereadded to 10 mL of Aqueous Solution 1 obtained in Example 1, and themixture was uniformly mixed, and then purified water was added theretoto give a final volume of 300 mL. The solution was filled asepticallyinto polyethylene bottles, thus obtaining a quick-drying rub-in-typehand disinfectant containing 0.2% olanexidine.

Preparation Example 12

6.3 g of a partially hydrolyzed polyvinyl alcohol, 1.8 g of lauric aciddiethanolamide and 3.6 g of a polyethylene-polypropylene glycol(polymerization degree of EO: 20; polymerization degree of PO: 20) wereadded to 20 mL of Aqueous Solution 2 obtained in Example 2, and themixture was uniformly mixed, adjusted to pH 4 to 7 by adding gluconicacid, and purified water was added thereto to give a final volume of 180mL. The solution was filled into polyethylene bottles, and high-pressuresteam sterilization was carried out, thus obtaining a disinfectantcontaining 2% olanexidine having the form of a scrub.

Preparation Example 13

40 g of a polyethylene-polypropylene glycol (polymerization degree ofEO: 20; polymerization degree of PO: 20) was added to 160 mL of AqueousSolution 3 obtained in Example 3, and the solution was filled intopolyethylene bottles, and then high-pressure steam sterilization wascarried out, thus obtaining a disinfectant containing 16% olanexidineintended for dilution at the time of use.

Preparation Example 14

0.9 g of a polyethylene-polypropylene glycol (polymerization degree ofEO: 20; polymerization degree of PO: 20) was added to 5 mL of AqueousSolution 2 obtained in Example 2, and the mixture was mixed uniformly,and purified water was added thereto to give a final volume of 90 L. Thesolution was filled aseptically into polyethylene bottles, thusobtaining a disinfectant containing 0.001% olanexidine.

Test Examples Skin Irritation Test

The hair on the back of rabbits was shorn off, and rabbits having noisland skin or wounds were selected. Each test preparation was openlyapplied to the rabbits once a day for four days. The second andsubsequent applications of the test preparation were carried out afterwiping the site of application with a cotton wool pad containing water.Evaluation was carried out once per day with regard to erythema andedema, and the total number of points for erythema and edema was takenas the evaluation score carried out in accordance with the followingjudgment criteria:

TABLE 1 Draize method judgement criteria Skin Erythema No erythema 0reaction Very slight erythema 1 judgment Clear erythema 2 criteriaMedium to severe erythema 3 Severe erythema (deep red color) 4 to slightcrust formation Edema No edema 0 Very slight edema 1 Clear edema 2Medium edema (approximately 1 mm) 3 Severe edema (more than 1 mm, 4spreads to surroundings)

The results are shown in Table 2 as mean values (n=6).

TABLE 2 Test Day 1 Day 2 Day 3 Day 4 Preparation (applied) (applied)(applied) (applied) Day 5 Day 6 Day 7 Day 8 Preparation 0 0 0 0 0 0 0 0Example 4 Preparation 0 0 0 0 0 0 0 0 Example 5 Preparation 0 0.2 0.20.2 0 0 0.2 0.2 Example 6 Preparation 0 0 0 0 0 0 0 0 Example 10Preparation 0 0 0 0 0 0 0 0 Example 14

As is clear from the results, the disinfectants of the present inventionhave essentially no problem with regard to skin irritation, and that inparticular the disinfectants of Preparation Examples 4, 5, 10 and 14, towhich a polyethylene-polypropylene glycol had been added, were excellentin terms of skin irritation.

Moreover, the disinfectants of Preparation Examples 1 to 14 exhibitedbactericidal action corresponding to the concentration of olanexidine,regardless of whether a polyalkylene glycol had been added thereto.

Reference Example 1 Preparation of Free Olanexidine

A 4 N aqueous sodium hydroxide solution (120 mL) was added to asuspension of olanexidine hydrochloride (40 g) in water (360 mL), andthe mixture was stirred for 90 minutes at 25° C. The crystals obtainedwere filtered off by suction filtration, washed with water (500 mL), andthen resuspended in water (500 mL). The suspension was stirred for 5minutes at room temperature (approximately 25° C.), and the crystalswere filtered off by suction filtration, and then washed with water (500mL). This operation (washing) was repeated once more. The crystalsobtained (wet weight: 127 g) were dissolved in methanol (200 mL), andthen water (60 mL) was added. The resulting emulsion was left for 12hours at room temperature, and then the crystals precipitated werefiltered off by suction filtration. The crystals were dried underreduced pressure at room temperature, whereby free olanexidine (32 g)was obtained.

Reference Example 2 Preparation of a D₂O Solution Containing 3%Olanexidine Gluconate

The free olanexidine obtained in Reference Example 1 (40 mg) wassuspended in D₂O (1 mL), a solution of gluconolactone (19.2 mg) in heavywater (1 mL) was added dropwise to the suspension, and the mixture wasstirred for 24 hours at room temperature, thus preparing a D₂O solutioncontaining olanexidine gluconate.

¹H-NMR (D₂O) δ (ppm): 0.75 (3H, t, J=7.1 Hz), 0.8-1.2 (12H, m), 2.6-2.8(2H, m), 3.4-3.7 (4H, m), 3.9-4.0 (2H, m), 4.07 (2H, br s), 6.90 (1H, d,J=7.9 Hz), 7.09 (1H, d, J=7.9 Hz), 7.13 (1H, s)

INDUSTRIAL APPLICABILITY

The aqueous solution of the present invention has a broad antibacterialspectrum, and a rapidly appearing and long-lasting bactericidalactivity. Therefore, the aqueous solution of the present invention isuseful as a medical disinfectant.

1. A method of disinfecting or sterilizing an object, comprisingcontacting the object with an effective amount of a disinfectantcontaining an aqueous solution containing1-(3,4-dichlorobenzyl)-5-octylbiguanide, at least an equimolar amount ofgluconic acid, a polyalkylene glycol selected from the group consistingof polyethylene-polypropylene glycol and polyethylene glycol, andwherein the concentration of an acid other than gluconic acid and a saltof the acid other than gluconic acid is not more than approximately0.05% (W/V), wherein the concentration of1-(3,4-dichlorobenzyl)-5-octylbiguanide is 0.1 to 20% (W/V), and theconcentration of the polyalkylene glycol is 0.01 to 10% (W/V).
 2. Themethod according to claim 1, wherein the disinfectant is an aqueouspreparation.
 3. The method according to claim 1, wherein thedisinfectant is an alcoholic preparation.
 4. The method according toclaim 3, wherein the concentration of1-(3,4-dichlorobenzyl)-5-octylbiguanide is 0.1 to 6% (W/V).
 5. Themethod according to claim 1, wherein the polyalkylene glycol is apolyethylene-polypropylene glycol.
 6. The method according to claim 5,wherein the polyalkylene glycol is a polyethylene-polypropylene glycolhaving a polymerization degree of ethylene oxide of about 10 to 300, anda polymerization degree of propylene oxide of about 10 to 100.